feat: add connection API endpoints

Suggestions, create/confirm/hide/withdraw actions, my connections list,
and pending count for nav badge.

server/api/connections/pending-count.get.js

@@ -0,0 +1,14 @@
+import Connection from '../../models/connection.js'
+import { requireAuth } from '../../utils/auth.js'
+
+export default defineEventHandler(async (event) => {
+  const member = await requireAuth(event)
+
+  const count = await Connection.countDocuments({
+    recipient: member._id,
+    status: 'pending',
+    hiddenBy: { $ne: member._id }
+  })
+
+  return { count }
+})